Huge heavy mod art glass ashtray, cobalt in crystal, vintage Murano?

Handcrafted freeform shape art glass ashtray, very heavy, 5 3/4" across x 4" tall. This is cobalt blue glass inside crystal clear glass, Murano style... though we're not sure it's Italian glass, as it's not marked at all. Maybe Chalet glass or similar?

The bottom has a little very fine scratching, but there are no other flaws at all. I believe this was probably a display piece, never actually used as an ashtray.